Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I cannot give a diagnosis, however I will try to provide you with information.

L5 sacralization is a common anatomical anomaly, where usually the L5 vertebral body becomes incorporated into the S1 vertebral body. It is a common finding in the general population, and is a benign process. This condition can be evaluated with plain x-rays, or CT scan. Sometimes an MRI may be helpful to assess other causes of back pain in patients with this condition.
For long time, the clinical significance of this condition has been debated, and it has usually been associated with low back pain, however there have been studies reporting no relationship between Lumbar sacralization and back pain. It has also been associated with “sciatic pain”, disc herniation, and nerve root entrapment with radiculopathy, producing basically radicular pain (pain radiating in the distribution of the root affected), sensory symptoms, or weakness.
This relationship are basically associations, and some patients can present with Lumbar sacralization without any symptoms.
As I said, many patients do not present with symptoms, and do not need any treatment. In your case, given the back pain, it may be important to make sure that there is no other cause of the back pain. An appropriate assessment will include a detailed history and physical examination including a neurologic examination, and if required, possibly some other images may be needed. If there is no other cause for the pain, medications for pain, and Physical Therapy are very helpful. Very rarely, surgical intervention is needed.
I think you should discuss your symptoms with your physician and discuss other alternatives for your back pain, including further work up, or treatment options.
I hope this is helpful. Good luck.

I tried PT for my sacralization with no change. I have extreme pain as the two bones involved literally grind against each other as I move around everyday. By the end of the day my pain is so intense I want to vomit and can't feel my right foot. Whoever says that there is no pain associated with this condition has obviously never had this condition themselves.

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